Welding gas

ABSTRACT

A welding gas composition having primary gas components which remain at a substantially uniformly high concentration as the gas is withdrawn from the cylinder and which also remain below the explosive limit, contains 1-35 molar percent of acetylene; 23-90 molar percent of propane, and/or propylene and/or cyclopropane, 8-75 molar percent of methylacetylene and/or propadiene, and 1-20 molar percent of paraffinic and/or olefinic C4-hydrocarbons.

United States Patent 1191 Meinass Mar. 12, 1974 [541 WELDING GAS 3,352,652 11/1967 Belfit 48/197 FM Inventor: Helmut Meinass winibaldstr. 819 3,226,213 12/1965 Nelson et a1. 48/197 FM Wolfratshausen, German I y Primary ExaminerS Leon Bashore [22] Flled: Apr- 19, 19 2 Assistant ExaminerRichard Pace [21] AppL No: 245 488 Attorney, Agent, or FirmMil1en, Raptes White [30] Foreign Application Priority Data [57] ABSTRACT Apr. 20, 1971' Germany 2119152 A Welding gas Composition having P y 3 p nents which remain at a substantially uniformly high 52 u.s. c1. 48/197 FM, 44/52 concentration as the gas is withdrawn from the y 51 Int. Cl (31013/02 der and which also remain below the explosive limit, [58] Field 01 Search 48/197 FM, 179; 44/52; contains molar percent of acetylene; 23-90 4 9; 252 372 molarpercent of propane, and/or propylene and/or p cyclopropane, 8-75 molar percent of methylacetylene [56] R fe Cited and/0r propadiene, and 1-20 molar percent of paraf- UNITED STATES A'TENTS finic and/or olefinic C --hydrocarbons. 3,706,542 12 1972 Gilks' 48/197 FM 8 Claims, 2 Drawing Figures SHEET 1 (IF 2 mmnsnm 12 mm PAIENTEB IIAR I 2 I974 SHEET 2 OF 2 1 WELDING GAS BACKGROUND OF THE INVENTION This invention relates to compositions of hydrocarbons suitable as welding gases. In German Pat. No. 1,221,758, there is disclosed as useful for welding, cutting, etc., a fuel gas mixture containing methylacetylene'and/or propadiene as the primary fuel in admixture with saturated and/or olefinic C and C hydrocarbons in specific percentages. In this mixture, the C and C.,hydrocarbons have the function ofmaintaining the concentration of the primary fuel components in-both the gas and liquid phases at below the explosive limit (75-78 molar percent) over the entire course of removal from the tank. This gaseous mixture also exhibits advantageous combustion properties, i. e., it has a high heating value, a high velocity of flame propagation and produces a high flame temperature upon combustion with oxygen. A disadvantage of thisgaseous mixture, however, resides in the fact that, when withdrawn from the gaseous phase, the lowerboiling components evaporate at a faster rate than the higher-boiling substances, so that the relative proportion of the higher-boiling components increases in the liquid remaining in the tank as well as in the gaseous phase in equilibrium therewith. Thus, as the container for the gas is emptied, the more reactive, but higherboiling primary fuels (methylacetylene and propadiene) become gradually enriched in the residue, and towards the end of the emptying step, the concentration of the highly reactive primary fuels is increased generally by 30 molar percent or more in the gaseous phase from beginning toend. Since the concentration of methylacetylene and propadiene must not exceed the explosive limit, it is essential to provide these components in a sufficiently low concentration in the filled tank so that the mixture remains stable during the entire course of withdrawal. Because of this necessary precaution, the concentration of primary fuels is low during a significant period at the early stages of withdrawal, and the resultant burning characteristics of the so evolved gas are relatively poor.

'As an alternative, in German Pat. No. 1,246,930,

there is disclosed a fuel gas mixture containing, in addition to high proportions of C hydrocarbons, 76-88 molar percent of methylacetylene andlor propadiene.

Since the aforesaid'range of 76-88 percent ovefiaps and exceeds the explosive limit of about 75-78 molar percent for methylacetylene and/or propadiene, such a gaseous mixture is unstable and thus dangerous to handle.

SUMMARY OF THE INVENTION Bearing in mind the deficiencies of the prior art, it is an object of the present invention to provide a fuel gas which is stable and also exhibits good combustion propmolar percent of methylacetylene and/or propadiene, and 1-20 molar percent of paraffinic and/0r olefmic C -hydrocarbons.

The introduction of acetylene as a primary fuel in addition to methylacetylene and/or propadiene is an important aspect of the present invention. Acetylene exhibits excellent combustion properties, in particular, a high flame propagation velocity and a high flame temperature. Moreover, since acetylene evaporates at a faster rate than the. remaining components of the mixture, the presence of a sufficient amount of primary fuel in the gaseous mixture is maintained at the beginning of and also throughout the withdrawalof gas. As the gaseous phase is removed from the container, the relativeproportion of acetylene decreases approximately to the extent that the proportion of methylacetylene and/or propadiene increases.

BRIEF DESCRIPTION OF DRAWINGS FIGS. 1 and 2 are graphs wherein the concentration -I( of the gaseous phase in equilibrium with liquid fuel gas mixture of a given composition'is plotted as the ordinate against the quantity M withdrawn from the tank in the gaseous phase as the abscissa, thev values being respectively molar percent.

DETAILED DISCUSSION Referring to FIGS. 1 and 2, the concentration of the initial liquid mixture and the temperature at which the measurements were conducted are set forth in the following table:

It can be seen that the concentration of the primary fuels (acetylene, propadiene, and methylacetylene) in the gaseous phase varies according to FIG. 1 between 64 and 73 molar percent, according to FIG. ,2 between 65 and .70 molar percent. Thus, the highest value and the lowest value for the concentration of the primary fuels in the gaseous'phase differ during the entire withdrawal period only be 9 and 5 molar percent, respectively. Consequently, by the present invention, it is possible to select the concentration of primary fuels so that it is substantially uniformly high and yet safely below the explosive limit. In this way, the excellent combustion properties of the primary gaseous components tending toward spontaneous decomposition can be utilized to their full extent. On the one hand, the tanks can be emptied completely without danger, and on the other hand, the combustion properties of the gaseous mixture remain practically unchanged during the entire withdrawal period.

The composition of the gaseous mixture drawn off from the vessel may, nevertheless, differ slightly depending on the velocity with which it is drawn off. So the mixtures of FIGS. 1 and 2 may assume the following compositions (on a molar percent basis) during a withdrawal period:

With respect to stability, it has been discovered that acetylene-containing fuel gas mixtures do not differ significantly from acetylene-free mixtures, as long as the total concentration of primary fuels remains the same. In any case, it is preferred that the concentration of methylacetylene and/or propadiene does not exceed 60 molar percent, in total.

percent of acetylene, 50-60 molar percent of methylacetylene and/or propadiene, -15 molar percent of A preferred fuel gas mixture consists of 5-10 iiii? l5 paraffinic and/or olefinic C hydrocarbons, and

-30 molar percent of propane and/or propylene and- /or cyclopropane.

The compositions of this invention can be produced conventionally by simple blending of the various components in the gaseous or liquid phase. The composition is usually stored in .a heavy walled pressure vessel, e.g a gas cylinder, under a pressure ranging from 85 to 170 psi at 20 C when the vessel is full. The fuel can be conventionally employed in the heating, cutting, welding etc. of metals, and for other uses where the combustion characteristics of the gas can be beneficially utilized.

When sold to consumers, the filled pressure vessels contain the mixture mainly in the liquid phase with only a very small amount in the gaseous phase, said mixture having the following range of compositions on a molar percent basis.

1 A fuel gas suitable for the heating, melting, welding, and cutting of metals, containing on a molar basis lpercent acetylene; 23-90 molar percent of a member selected from the group consisting of propane, propylene, cyclopropane, and mixtures thereof; 8-75 percent of a member selected from the group consisting of methylacetylene, propadiene, and mixtures thereof; and l-20 percent of a member selected from the group consisting of n-butanefisobutane, l butene, isobutene, 1,3-butadiene and mixtures thereof.

2. A fuel gas as defined by claim 1, containing 5-10 percent 'of acetylene, 20-30 percent of a member selected from the group consisting of propane, propylene, cyclopropane, and mixtures thereof; -60 percent of a member selected from the group consisting of methylacetylene, propadiene, and' mixtures thereof; and 5-1 5 molar percent of a member selected from the group consisting of n-butane, isobutane, l-butene, isobutene, 1,3-butadien.

3. A fuel gas as defined by claim 1 wherein the molar percent of the sum of acetylene, propadiene and methylacetylene is 8-75 percent, and the sum of propane, propylene, cyclopropane, n-butane, isobutane, lbutene, isobutene, and 1,3-butadiene is 25-65 percent.

7 4. A fuel gas as defined by claim 2 wherein the molar percent of the sum of acetylene, propadiene and methylacetylene is -70 percent, and the sum of propane, propylene, cyclopropane, n-butane, isobutane, lbutene, isobutene, and 1,3-butadiene is 30-40 percent.

5. A vessel under a pressure of -170 psi at 20 C containing in mainly the liquid form fuel gas as defined by claim 1.

6. A vessel under a pressure of 85-170 psi at 20C A General Preferred A. Acetylene l 35 5 10 B. Propadiene and/or methylacetylene 8 75 50 60 C.2A+B 35-75 60-70 D. Propane, propylene and/or 23 20 30 cyclopropane E. n-Butane, isobutane, l-butene, isobutene, l 20 S 15 and/or 1,3-butadiene F.2D+E. 25-65 30-40 From the foregoing description, one skilled in the art can easily ascertain the essential charactersitics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be within the full range of equivalence of the following clairns What is lai medis:

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 r 796 r 554 Dated March 12 1974 InVentor(s) Helmut elnass It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE HEADING, INSERT THE ASSIGNEE OF RECORD :v

Linde Aktiengesells'chaft, Wiesbaden, Germany Signed and sealed this 17th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PC4050 (10459) USCOMM-DC 60376-F'69 UIS. GOVERNMENT PRINTING OFFICE: I969 0-466-334, 

2. A fuel gas as defined by claim 1, containing 5-10 percent of acetylene, 20-30 percent of a member selected from the group consisting of propane, propylene, cyclopropane, and mixtures thereof; 50-60 percent of a member selected from the group consisting of methylacetylene, propadiene, and mixtures thereof; and 5-15 molar percent of a member selected from the group consisting of n-butane, isobutane, 1-butene, isobutene, 1,3-butadien.
 3. A fuel gas as defined by claim 1 wherein the molar percent of the sum of acetylene, propadiene and methylacetylene is 8-75 percent, and the sum of propane, propylene, cyclopropane, n-butane, isobutane, 1-butene, isobutene, and 1,3-butadiene is 25-65 percent.
 4. A fuel gas as defined by claim 2 wherein the molar percent of the sum of acetylene, propadiene and methylacetylene is 60-70 percent, and the sum of propane, propylene, cyclopropane, n-butane, isobutane, 1-butene, isobutene, and 1,3-butadiene is 30-40 percent.
 5. A vessel under a pressure of 85-170 psi at 20* C containing in mainly the liquid form fuel gas as defined by claim
 1. 6. A vessel under a pressure of 85-170 psi at 20*C containing in mainly the liquid form fuel gas as defined by claim
 2. 7. A vessel under a pressure of 85-170 psi at 20*C containing in mainly the liquid form fuel gas as defined by claim
 3. 8. A vessel under a pressure of 85-170 psi at 20*C containing in mainly the liquid form fuel gas as defined by claim
 4. 